1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method with which it is possible to perform, by means of propagating ultrasonic waves, predetermined processing, such as cleaning, on various types of substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays and optical disk substrates.
2. Description of the Relates Art
A conventional approach to remove extremely small contaminants such as particles adhering upon a substrate is to apply ultrasonic vibration upon a processing liquid and propagate the ultrasonic vibration to the substrate while supplying the processing liquid to the substrate. The application of physical vibration originating from the ultrasonic waves in addition to chemical cleaning owing to the processing liquid achieves better cleaning of the substrate and effective removal of particles. A method of cleaning the substrate in this fashion may be a batch-type cleaning method which requires immersion of many substrates at once into a processing liquid or a single wafer-type cleaning method which requires processing one substrate at a time while supplying a processing liquid to a surface of the substrate.
Published Japanese Translation of PCT International Application No. P2004-515053A for instance describes a certain apparatus as a single wafer-type substrate processing apparatus. In this apparatus, at least one ultrasonic transducer is buried in an opposed member (platter) in the proximity of the back surface (non-device seating surface) of a substrate so that ultrasonic vibration propagate to the substrate via a chemical agent which is in contact with both the substrate and the opposed member. Some ultrasonic waves entering the back surface of the substrate are transmitted through the substrate and reaches the front surface (device seating surface) of the substrate. With the chemical agent supplied to the front surface of the substrate from a nozzle which is disposed above the substrate, the chemical agent vibrates because of the ultrasonic waves propagating to the front surface of the substrate. In this manner, the chemical agent to which the ultrasonic vibration has added cleans the front surface of the substrate.
Meanwhile, in the apparatus described in Japanese Patent Application Unexamined Publication No. H8-130202, an ultrasonic transducer is built within a processing liquid guide which is disposed opposing the front surface of a substrate and supplies a processing liquid to the front surface of the substrate, thereby enhancing the cleaning effect with ultrasonic vibration propagating to the processing liquid.